merge from develop & refact config reader

[fangyincheng]

What this PR does:

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-io]

Codecov Report

Merging #410 into feature/rest will decrease coverage by 0.19%.
The diff coverage is 55.71%.

@@               Coverage Diff                @@
##           feature/rest     #410      +/-   ##
================================================
- Coverage         67.63%   67.44%   -0.20%     
================================================
  Files               170      169       -1     
  Lines              8655     8579      -76     
================================================
- Hits               5854     5786      -68     
+ Misses             2256     2249       -7     
+ Partials            545      544       -1     

Impacted Files	Coverage Δ
common/extension/confit_reader.go	0.00% <0.00%> (ø)
config/base_config.go	64.14% <ø> (ø)
config/generic_service.go	0.00% <ø> (ø)
config_center/parser/configuration_parser.go	2.25% <0.00%> (+0.17%)	⬆️
config/config_loader.go	56.91% <14.28%> (-6.81%)	⬇️
common/proxy/proxy.go	93.06% <25.00%> (-1.98%)	⬇️
protocol/rest/config/reader/rest_config_reader.go	80.26% <81.81%> (ø)
common/yaml/yaml.go	100.00% <100.00%> (ø)
config/consumer_config.go	56.25% <100.00%> (+0.93%)	⬆️
config/provider_config.go	59.37% <100.00%> (+1.31%)	⬆️
... and 10 more

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[flycash]

I find out that users may be confused about the config reader because only rest protocol uses this interface. But the most important config like application config, consumer config, provider config... do not use this interface.

It should be refactored in the future.